[Qemu-devel] [RFC PATCH v1 2/3] gluster: Implement .bdrv_co_write_zeroes for gluster

[Bharata B Rao <bharata@linux.vnet.ibm.com>]

Support .bdrv_co_write_zeroes() from gluster driver by using GlusterFS API
glfs_zerofill() that off-loads the writing of zeroes to GlusterFS server.

Signed-off-by: Bharata B Rao <bharata@linux.vnet.ibm.com>
---
 block/gluster.c | 77 +++++++++++++++++++++++++++++++++++++++++++++------------
 configure       |  8 ++++++
 2 files changed, 69 insertions(+), 16 deletions(-)

diff --git a/block/gluster.c b/block/gluster.c
index 88ef48d..1390270 100644
--- a/block/gluster.c
+++ b/block/gluster.c
@@ -245,6 +245,22 @@ static void qemu_gluster_complete_aio(void *opaque)
     qemu_coroutine_enter(acb->coroutine, NULL);
 }
 
+/*
+ * AIO callback routine called from GlusterFS thread.
+ */
+static void gluster_finish_aiocb(struct glfs_fd *fd, ssize_t ret, void *arg)
+{
+    GlusterAIOCB *acb = (GlusterAIOCB *)arg;
+
+    acb->ret = ret;
+    acb->bh = qemu_bh_new(qemu_gluster_complete_aio, acb);
+    qemu_bh_schedule(acb->bh);
+}
+
+static const AIOCBInfo gluster_aiocb_info = {
+    .aiocb_size = sizeof(GlusterAIOCB),
+};
+
 /* TODO Convert to fine grained options */
 static QemuOptsList runtime_opts = {
     .name = "gluster",
@@ -317,6 +333,39 @@ out:
     return ret;
 }
 
+#ifdef CONFIG_GLUSTERFS_ZEROFILL
+static int qemu_gluster_co_write_zeroes(BlockDriverState *bs,
+        int64_t sector_num, int nb_sectors)
+{
+    int ret;
+    GlusterAIOCB *acb;
+    BDRVGlusterState *s = bs->opaque;
+    off_t size;
+    off_t offset;
+
+    offset = sector_num * BDRV_SECTOR_SIZE;
+    size = nb_sectors * BDRV_SECTOR_SIZE;
+
+    acb = qemu_aio_get(&gluster_aiocb_info, bs, NULL, NULL);
+    acb->size = size;
+    acb->ret = 0;
+    acb->coroutine = qemu_coroutine_self();
+
+    ret = glfs_zerofill_async(s->fd, offset, size, &gluster_finish_aiocb, acb);
+    if (ret < 0) {
+        ret = -errno;
+        goto out;
+    }
+
+    qemu_coroutine_yield();
+    ret = acb->ret;
+
+out:
+    qemu_aio_release(acb);
+    return ret;
+}
+#endif
+
 static int qemu_gluster_create(const char *filename,
         QEMUOptionParameter *options, Error **errp)
 {
@@ -359,22 +408,6 @@ out:
     return ret;
 }
 
-static const AIOCBInfo gluster_aiocb_info = {
-    .aiocb_size = sizeof(GlusterAIOCB),
-};
-
-/*
- * AIO callback routine called from GlusterFS thread.
- */
-static void gluster_finish_aiocb(struct glfs_fd *fd, ssize_t ret, void *arg)
-{
-    GlusterAIOCB *acb = (GlusterAIOCB *)arg;
-
-    acb->ret = ret;
-    acb->bh = qemu_bh_new(qemu_gluster_complete_aio, acb);
-    qemu_bh_schedule(acb->bh);
-}
-
 static coroutine_fn int qemu_gluster_co_rw(BlockDriverState *bs,
         int64_t sector_num, int nb_sectors, QEMUIOVector *qiov, int write)
 {
@@ -567,6 +600,9 @@ static BlockDriver bdrv_gluster = {
 #ifdef CONFIG_GLUSTERFS_DISCARD
     .bdrv_co_discard              = qemu_gluster_co_discard,
 #endif
+#ifdef CONFIG_GLUSTERFS_ZEROFILL
+    .bdrv_co_write_zeroes         = qemu_gluster_co_write_zeroes,
+#endif
     .create_options               = qemu_gluster_create_options,
 };
 
@@ -588,6 +624,9 @@ static BlockDriver bdrv_gluster_tcp = {
 #ifdef CONFIG_GLUSTERFS_DISCARD
     .bdrv_co_discard              = qemu_gluster_co_discard,
 #endif
+#ifdef CONFIG_GLUSTERFS_ZEROFILL
+    .bdrv_co_write_zeroes         = qemu_gluster_co_write_zeroes,
+#endif
     .create_options               = qemu_gluster_create_options,
 };
 
@@ -609,6 +648,9 @@ static BlockDriver bdrv_gluster_unix = {
 #ifdef CONFIG_GLUSTERFS_DISCARD
     .bdrv_co_discard              = qemu_gluster_co_discard,
 #endif
+#ifdef CONFIG_GLUSTERFS_ZEROFILL
+    .bdrv_co_write_zeroes         = qemu_gluster_co_write_zeroes,
+#endif
     .create_options               = qemu_gluster_create_options,
 };
 
@@ -630,6 +672,9 @@ static BlockDriver bdrv_gluster_rdma = {
 #ifdef CONFIG_GLUSTERFS_DISCARD
     .bdrv_co_discard              = qemu_gluster_co_discard,
 #endif
+#ifdef CONFIG_GLUSTERFS_ZEROFILL
+    .bdrv_co_write_zeroes         = qemu_gluster_co_write_zeroes,
+#endif
     .create_options               = qemu_gluster_create_options,
 };
 
diff --git a/configure b/configure
index 0666228..886d71b 100755
--- a/configure
+++ b/configure
@@ -255,6 +255,7 @@ coroutine_pool=""
 seccomp=""
 glusterfs=""
 glusterfs_discard="no"
+glusterfs_zerofill="no"
 virtio_blk_data_plane=""
 gtk=""
 gtkabi="2.0"
@@ -2673,6 +2674,9 @@ if test "$glusterfs" != "no" ; then
     if $pkg_config --atleast-version=5 glusterfs-api; then
       glusterfs_discard="yes"
     fi
+    if $pkg_config --atleast-version=6 glusterfs-api; then
+      glusterfs_zerofill="yes"
+    fi
   else
     if test "$glusterfs" = "yes" ; then
       feature_not_found "GlusterFS backend support"
@@ -4175,6 +4179,10 @@ if test "$glusterfs_discard" = "yes" ; then
   echo "CONFIG_GLUSTERFS_DISCARD=y" >> $config_host_mak
 fi
 
+if test "$glusterfs_zerofill" = "yes" ; then
+  echo "CONFIG_GLUSTERFS_ZEROFILL=y" >> $config_host_mak
+fi
+
 if test "$libssh2" = "yes" ; then
   echo "CONFIG_LIBSSH2=y" >> $config_host_mak
 fi
-- 
1.7.11.7